The present invention relates to a process for flow forming. Existing manufacturing techniques for forming a desired structure from a preform often require substantial machining of the shape or joining together of a number of parts to form the desired structure. This normally results in wastage of material of the preform, extra processing steps, and a possibly weakened structure at the joint of a plurality of preforms. This results in undesirable increased costs and time consumption in processing the preform.
The present invention relates to a process where parts are formed to substantially net shape to thereby reduce conventional machining and obivate the need where possible for a plurality of parts which must be joined to form the final structure. Flow forming is a process where a part is formed by the use of heat and compressive pressure. It is to be distinguished from superplastic forming where parts are drawn under tensile stress. The part to be formed is placed within tooling and heated to the temperature at which the part material becomes plastic. Pressure is then applied to the tooling to flow the part material into the shape dictated by the tooling.
A method seeking to overcome the aforementioned disadvantages of the prior art is described in U.S. Pat. No. 3,519,503 to Moore, et al. In this method high strength alloys are heated to a temperature placing them in a condition of low strength and high ductility and forged in hot dyes to a desired shape. However, structures requiring large deformation are either not possible or excess time consumption is required for flow of the preform to the desired shape. Additionally, problems result in removing the formed part from the structure.